Effects of vitamin C and vitamin E on in vivo lipid peroxidation: results of a randomized controlled trial.

Randomized controlled trial of 184 community-dwelling nonsmoking adults recruited in the greater Baltimore, Maryland, area between February 1996 and June 1997. Participants were allocated to placebo, vitamin C alone, vitamin E alone, or vitamin C plus vitamin E; a small subgroup analysis also evaluated 44 participants with low baseline vitamin E intake.

Participants were assigned to oral vitamin C 500 mg/day, oral vitamin E 400 IU/day (RRR-alpha-tocopheryl acetate), both vitamins together at the same daily doses, or matching placebos for 2 months. The active regimens were administered as 2 daily pills (vitamin C or placebo and vitamin E or placebo).

Vitamin C or vitamin E alone reduced in vivo lipid peroxidation to a similar extent, but combining the two vitamins did not add benefit beyond either vitamin alone. For urinary creatinine-adjusted 8-iso-PGF2alpha, mean change was 9.0 with placebo, -150.0 with vitamin C, -141.3 with vitamin E, and -112.5 with vitamins C + E; the interaction was not significant (P = 0.12). Neither vitamin affected urinary MDA + 4-hydroxyalkenals, but vitamin C significantly increased serum ORAC (P = 0.01). Serum ascorbic acid and alpha-tocopherol concentrations increased in the active vitamin groups.

Treatment duration was short at 2 months, and no adverse events were reported. Baseline race and serum ascorbic acid differed by group, which may complicate interpretation, and some biomarker analyses were based on small subgroups, including the GC-MS analysis in 44 participants. Generalizability is limited to community-dwelling nonsmokers in one U.S. region.